Why is software testing necessary?

Software Testing is necessary because we all make mistakes. Some of those mistakes are unimportant, but some of them are expensive or dangerous. We need to check everything and anything we produce because things can always go wrong – humans make mistakes all the time.
Since we assume that our work may have mistakes, hence we all need to check our own work. However some mistakes come from bad assumptions and blind spots, so we might make the same mistakes when we check our own work as we made when we did it. So we may not notice the flaws in what we have done.
Ideally, we should get someone else to check our work because another person is more likely to spot the flaws.
There are several reasons which clearly tells us as why Software Testing is important and what are the major things that we should consider while testing of any product or application.

Software testing is very important because of the following reasons:

Software testing is really required to point out the defects and errors that were made during the development phases.

It’s essential since it makes sure of the Customer’s reliability and their satisfaction in the application.

It is very important to ensure the Quality of the product. Quality product delivered to the customers helps in gaining their confidence. (Know more about Software Quality)

Testing is necessary in order to provide the facilities to the customers like the delivery of high quality product or software application which requires lower maintenance cost and hence results into more accurate, consistent and reliable results.

Testing is required for an effective performance of software application or product.

It’s important to ensure that the application should not result into any failures because it can be very expensive in the future or in the later stages of the development.

It’s required to stay in the business.

What is functionality testing in software?

Functionality testing is performed to verify that a software application performs and functions correctly according to design specifications. During functionality testing we check the core application functions, text input, menu functions and installation and setup on localized machines, etc.

The following is needed to be checked during the functionality testing:

Text input, including the use of extended characters or non-Latin scripts.

Core application functions.

String handling, text, and data, especially when interfacing with non-Unicode applications or modules.

Regional settings defaults.

Text handling (such as copying, pasting, and editing) of extended characters, special fonts, and non-Latin scripts.

Text handling (such as copying, pasting, and editing) of extended characters, special fonts, and non-Latin scripts.

Accurate hot-key shortcuts without any duplication.

Functionality testing verifies that an application is still fully functional after localization. Even applications which are professionally internationalized according to world-readiness guidelines require functionality testing.

What is Non-functional testing in software?

In non-functional testing the quality characteristics of the component or system is tested. Non-functional refers to aspects of the software that may not be related to a specific function or user action such as scalability or security. Eg. How many people can log in at once? Non-functional testing is also performed at all levels like functional testing.